+ hg init
+ hg add a b
+ hg commit -m commit #0 -d 0 0
+ hg commit -mcomment #1 -d 0 0
+ hg update 0
+ hg commit -A -mcomment #2 -d 0 0
removing b
+ hg update 1
this update spans a branch affecting the following files:
 b
aborting update spanning branches!
(use update -m to merge across branches or -C to lose changes)